1. Field of the Invention
The present invention relates to an apparatus for producing a honeycomb body used in catalytic purification of exhaust gas of an internal combustion engine. In particular, the present invention relates to an apparatus for producing a honeycomb body, which can produce precise dimensions for accurately inserting said honeycomb body of a spiral form into a metal outer shell, wherein said honeycomb body is made by folding a flat sheet and a corrugated sheet into a roll.
2. Description of the Related Art
In general, the support for catalytic purification of exhaust gas includes an outer shell of a cylindrical metal material, wherein a honeycomb body is inserted and joined thereto. The methods of inserting a honeycomb body into a metal outer shell can be classified into two main types. First is a method of inserting a honeycomb body into a pre-joined outer shell in the shape of a pipe as described in Japanese Patent Nos. 5-228376, 6-390, 6-391, 6-47284, 6-63421, 6-182222, 6-238174, 7-24330, 8-206512; and U.S. Pat. No. 5,366,700, which is incorporated by reference as if fully set forth herein. Second is a method of inserting a honeycomb body into a non-joined outer shell in the shape of a xe2x80x9cCxe2x80x9d or into an outer shell of several pieces cut lengthwise, followed later by joining of the outer shell as described in Japanese Patent Nos. 4-122418, 5-220404, 6-269683, 6-277527; and U.S. Pat. No. 5,316,997, which is incorporated by reference as if fully set forth herein.
If the outer diameter of the honeycomb body is less than the inner diameter of the outer shell, the outer shell and the honeycomb may become separated due to improper joining therein. On the other hand, if the outer diameter of the honeycomb is larger than the inner diameter of the outer shell, it is impossible to insert the honeycomb into the outer shell without damaging the shape thereof. Even if a forceful insertion can be made with ensuing damages to the shape, it would be followed by non-uniformity with respect to overall joining which may cause problems for permeability.
For this reason, it is desirable to produce a honeycomb with a certain set of dimensions. The methods used may be classified into two major types. The first method involves direct control by measuring the diameter or radius of the honeycomb body in a roll (hereinafter referred to as a method of measuring outer diameter, Japanese Patent No. 4-371234, which is incorporated by reference as if fully set forth herein). The second method involves indirect control over the length of the strip used during the winding process of a honeycomb body (hereinafter referred to as a method of measuring length).
The method of measuring the outer diameter involves a honeycomb body, produced by a winding process, which is of a warped spiral shape, and not a round form. Hence, even if a honeycomb body were to be produced, which perfectly matches the inner diameter of an outer shell at one point of measurement, it would be considerably larger or lesser than the inner diameter of the outer shell at some other points of measurement. Consequently, it is very difficult to insert a honeycomb body into the outer shell, although it may potentially be capable of accurate insertion into the outer shell. Moreover, even if a standard for accurate insertion into the outer shell could be made by many trials and errors, there still is the disadvantage of necessarily carrying out another set of trials and errors due to the changes in the dimensions of the outer shell. Therefore, this method may be applied to mass production of a small number of limited product types, yet may be inappropriate for small-lot production of a variety of product types.
The method of measuring length obviously brings about many trials and errors due to its indirect control method. However, there is a problem relating to tension in effect during the winding process. It is necessary to control the tension to the flat sheet or corrugated sheet during the winding process in order to increase its structural tightness and mechanical strength. In this case, if the tension being controlled changes to the slightest extent, the size of the cell changes. As the size of the cell changes, the length of the strip used to produce honeycomb bodies of the same dimensions changes. Consequently, it becomes difficult to control the dimensions of a honeycomb by using the length of the strip used in the overall process. Therefore, in using the method of measuring length, it is impossible to consistently produce honeycomb bodies with a certain set of dimensions if the reproduction is not carried out perfectly with respect to additional conditions of tension from the start of the winding process to its end.
An embodiment includes an apparatus for producing a honeycomb body, which can produce precise dimensions for accurately inserting the same into a metal outer shell, wherein a spiral shaped honeycomb body is made by folding a flat sheet and-a corrugated sheet into a roll.
The embodiment includes a roll part for supplying a thin metal flat sheet via several rolls; a part for measuring the length of feed of the flat sheet which is fed through said roll part; a roll to part for supplying a corrugated sheet to overlap the same onto said flat sheet via several rolls; a winding roll of a honeycomb body which is made by folding the overlapping flat and corrugated sheets into a roll; a part for measuring the rotation angle of said winding roll; and a control part which controls the amount of winding in a roll of a honeycomb body by means of computing the measurement values from said part for measuring the length and said part for measuring the rotation angle.